The present invention relates to an improved steel rolling door particularly equipped with a number of consecutively connected pivot plates and a plurality of pulling wires and a plurality of length variable linkage assembly units which are engaged with a plurality of horizontal collapsible door plates in such a manner that the rolling collection of the rolling door can operate in a smooth way without getting stuck in one aspect and make the door plates adjustable between a horizontal position and a vertical position in another aspect.
Steel rolling doors have been popularly employed by stores in most big cities for security reasons. As shown in FIG. 2, the conventional steel rolling door 1 is generally equipped with a plurality of collapsible door plates 12 and a plurality of supporting rods 11, and a plurality of pivotal linking pieces 13 and a stop member 15 disposed at each end of the door plates 12 for retaining the supporting rods in place. The longitudinal edges of the plates 12 are curvedly bent in such a manner that the supporting rods 11 can be confined thererin. This door 1 can be adjusted to permit air and light to come in or to be blocked out by varying the angle of the door plates between a horizontal position and a vertical position piece by piece when the rolling door is put down.
As shown in FIGS. 3, 4, the adjustment of the angle of the door plates 12 can be effected by a slidable wall plate 22 disposed inside each slide track 2. Each slidable wall plate 22 is equipped with a pair of spring biased connecting rods 23 which can retractably pull the slidable wall plate 22 to one side and limit the door plates in a vertical position and the door plates 12 can only be turned horizontally and limited in that position when the door plates fully extend to the bottom and abut against the ground, forcing both the wall plates 22 in the slide tracks 2 to move to one side so as to permit the door plates 22 to turn horizontally and retained in that position. To roll the door 1 up, the door plates 12 are pivoted again vertically and retained in that state by the slidable wall plate 22.
Although, the door plates 12 of such conventional rolling door 1 can be adjusted in the operation angle thereof, they are not equipped with any adjusting device, making the adjustment difficult to effect. Moreover, the length of all the linking pieces 13 disposed between the door plates 12 is fixed and identical; thus, the door plates 12 can easily get stuck in a rolling operation.